During the past four years, our research team has been engaged in a project aimed at organizing a complex multivariate database on sexual offenders into homogenous and reliable scales and dimensions for the purpose of generating useful taxonomies of this important, but inadequately studied, offender sample. Initial reliability and concurrent validity results of both our clinical and empirical strategies of clustering life history and offense data have been very promising. These results, however, have been based on a rather select sample--offenders currently committed to the Massachusetts Treatment Center as "sexually dangerous persons" --and have relied solely on concurrent data sources. The practical usefulness of our taxonomic solutions can only be evaluated in the context of generalization and follow-up data. The proposed research, therefore, aims at: (1) assessing the generalization and coverage of our typologies when applied to (a) the large sample of offenders observed at the Massachusetts Treatment Center and found to be "not sexually dangerous" and (b) a smaller sample of sexual offenders seen at the Oak Ridge Division of the Mental Health Centre in Penetanguishene, Ontario, Canada; (2) examining the cross-situational and prognostic utility of our dimensions and types by a follow-up of released sexual offenders (both "sexually dangerous" and "not sexually dangerous") through state and federal records; (3) using this follow-up data also as a means of unconfounding or collapsing subtypes as a function of their predictive validity; and (4) beginning to asses aspects of person-situation interactions and institutional programs as they affect post-release outcome and recidivism. The significance of the proposed research lies primarily in the benefits a valid, predictive, widely applicable taxonomy would have both for subsequent research into the etiology, diagnosis, treatment, and management of sexual aggression and for the elucidation this admittedly preliminary data would provided for current decision-making about such offenders.